I have a 1994 Rheem 1 stage cool, 2 stage heat system. In summary the system is a heat pump. The heat pump can be used to cool or heat the house. The 2nd stage of heat is electric.

In wiring a new Lux 1 stage cool, 2 stage heat thermostat, I am left with two active wires that go some where out to the heat pump. Blue & Brown.. I am assuming that the blue wire goes to the B terminal on the thermostat, however the brown wire is a mystery. This appears to be a 7-wire system with one transformer.

All the info I can find on the net is for 7-wire 2 transformer or 1 transformer 6-wire systems heat pump systems, where blue is optional. Perhaps the brown wire has something to do with emergency / auxilary heat? The black wire is not used nor is it connected to anything at the furnace. Just guessing... Ideas?

 

I will try to help you out.BUT without a wiring it is hard.1st place your unit to emergency heat,if you do not get heat from the unit the brown lead "MAYBE" your emergency heat (the same heat that tempers your air in the reverse cycle).There is no complete universal configuration.EVERY manufacturer seems to different numbers,different letter codes for their wiring schemes.If you do not get eheat the brown wire "MAY" go to the eheat.York uses "B" as it's power 24 volts to control the circuits.If you have a voltmeter,place unit to eheat,check brown wire to ground,if it shows 24 volts,this could be your eheat circuit.Take unit out of eheat,check your voltage to ground.Do same to blue wire.Do not attach any wires unit you are sure.They do not give transformers away.If all else fails call Lux or the tstat supplier and say you need assistance for the product you purchased.Keep in touch.PDF

 

Sorry guy I left you hanging when I stated York uses "B" as power.Yes "B" is brown, "B" is for black, "B" is for blue.York uses "B" for BLUE.It is thje 24 volt circuit.See what I mean.If all manufacturers used the same coding system for wiring it would make everything a lot easier for TECHS and customers.PDF

 

Let's try this, you have a Lux digital Universal heat pump t'stat. First, I hope you wrote down the wire designations and color from your old t'stat. Here is what the designations mean. Let's not worry so much about color. R=power from control transformer to t'stat
G=power to the fan
O=power to the reversing valve in cool mode
B=power to the reversing valve in heat mode
E=power to Aux/em heat in em.heat mode
W2=power to aux/em heat in normal operation
C= common
You need to know whether your heat pump is energinzing the reversing valve in heat or cool.

 

The old thermostat had a connection for EC, the new Lux thermostat does not. I think that is where the brown wire went to.. What is Aux/Emergency Heat and how does it work? Will I damage the system if this wire is not connected...
W=White
O=Orange
R=Red
B=Blue
G=Green
Y=Yellow
?=Brown

The heat pump outside the house is blowing cold air in heat mode and hot air in ac mode, which is what I think it is supposed to do. So I think that means I have the reversing valve connections correct.

[Edited by dodgegreen on 11-30-00 at 02:13]

 

Can any one confirm this brown wire issue?

 

Go back to my thread.If you checked the system in all modes; emergency heat,HP heat,etc and all phases of your system are operating as they should it is possble the brown lead is not needed.Have you noticed any component not functioning?PDF

 

I would suggest you pull the wiring schemetic off of your heat pump or your air handling unit. It will show you where all the designated wire connections.

 

Yes all components appear to be operating correctly. There is no schematic on the heat pump, missing I guess. Rheem says this model is capable of supporting Aux Heat but wiring may be non-standard based on how the unit was wired by the technician, so they are hesitant to make any speculations on the brown wire, which appears to go to the outside heat pump. Obvously Rheem suggests calling a certified Rheem technician.

I guess if the system appears to work fine I will leave as is... I still would like someone to provide a definition of Aux / Emegergency Heat and how it works.

 

Aux/em heat are your electric heat coils in the air handling unit. They are the 2nd stage heat for your heat pump when the outdoor temp. gets low enough that the heat pump can not bring the house up to temp. by itself. The Em heat is the same set of heat coils, but sometimes, when it is very cold/or the outdoor unit craps out, you can switch to Emergancy heat. This will shut down the heat pump and use the coil heaters as your 1st stage heat.

 

That is interesting... How cold would the outside temp need to be to cause damage to the heat pump if aux / emer heat came on and the heat pump came on also?

Is there such a thing as Efficency Heat mode, where stage 1 & 2 are used to bring the house up to temp in the house, then only the heat pump is used to maintain the temp?

[Edited by dodgegreen on 12-06-00 at 01:01]

 

Dodgegreen....Theoretically your heat pump should provide heat to your home until the outside temp is -459.66 degrees Fahrenheit.Absolute 0 is -459.67.Sometimes in Maine,in late January it does feel that cold.Your heat pump is designed to remove heat from the outside air and deliver it to your blower (your indoor unit) and disperse it thru out your home.
I realize it's hard to believe when you walk outside;the temp is only 24 degrees,and PDF says "Yes there is heat in the air." I also do alot of refrigeration work.When I work in a walkin freezer that is 10 degrees below 0,then walk into the walkin cooler that is at 40 degrees IT FEELS WARM....!!!!!!!
Don't worry about damage to your heat pump because of low outside temps.The HP compressor is a beefed up version of a plain A/C compressor.
What your HP does is extract heat from the outside at a lower cost per KW than your electric backup heat.Then as the outside temp drops(less heat in the outside air)your HP efficiency drops off.Your temp indoors drops,the tsat senses this,CLICKS and brings on your your emergency or backup heat,of course at a higher KW or higher electric bill.This added heat warms the tstat up to the point where it shuts off the backup heat.Then your back on HP only.Your unit will keep shifting back between these to modes to keep you and yours warm and happy.
One other thing the backup does...When your out door unit reverses cycle to clear it of ice and frost it brings on the backup so you do not run strict A/C into your home.
All else said who was FAHRENHEIT????Well about 260 years ago GABRIEL DANIEL FAHRENHEIT set the standard for water freezes at 32 degrees.YEP it's hard to believe but at 32 degrees ice still has alot of heat to release.Well Mr. Dodgegreen I quess I have bored you enough for one evening.Have a GREAT and SAFE HOLIDAY!!!!!!!!!!!!PDF

 

How does the tstat know what the outside temp is in order to turn off the HP? Is this something built into the HP? --or-- are you saying when the tstat senses that the indoor temp is below a certain temp, i.e 32F, it assumes that it is to cold outside to run the HP effciently. If so, and the house comes up to temp just on electric heat, then how does the system know to keep the HP off? If lets say the brown wire goes from the tstat EM / Aux Heat terminal to the outdoor HP, is the tstat telling the HP to kick off, thus overiding the normal heat / cool - valve reversal request from the tstat?

Perhaps this would make sense if in fact the brown wire enabled the electric heat relay only. But in this case it appears to go directly to the HP --or-- if the brown wire was used by the HP to notify the tstat that it is to cold to operate in heat mode efficiently, thus forcing the tstat to engage electric heat only.

 

Your t'stat does not sense the outdoor temp. And yes, when your heat pump goes into defrost it sends a signal back to the electric heat to come on to heat the a/c air.

 

Thanks all, I think the light is finally coming on over my head.Did'nt realize the complexity of these HP systems and modes. Wish there was standardized wire color coding and docs on this stuff. Seems most differ past a typical 4 or 5 wire tstat setup.It is better to ask, than to pay $'s to have a tech come out and shake his head at me and much less expensive than replacing or damaging the HP.

Feel free to post any aditional FYI's should they come to mind. I will continue to check this forumn for a while.

 

From PDF: "The tstat I am talking about is inside your house mounted on the wall.Look at it this way...If you had 2 stats mounted on the wall,one was set at 72 to bring your HP on,the heat pump would start;thus suppling you heat.Let's say the other tstat is set for 68.When your room temp hit 68 your heat pump would keep running but the tsat set at 68 would bring on your extra heat;;;emer,backup,elect.When the room temp gets to 70 the elect heat shuts down,the heat pump keeps going until it satisfies the tstat you have set at 72."

Thanks PDF